Paperboard stack cover



FIG. 1 is a top plan view of a paperboard stack cover showing my new design;

FIG. 2 is a bottom plan view thereof;

FIG. 3 is an end elevational view thereof, the other end view thereof being a mirror image of this view, and,

FIG. 4 is a side elevational view thereof, the other side view being a mirror image of this view. 

The ornamental design for a paperboard stack cover, as shown and described. 